<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>22.生成器函数实例</title>
</head>
<body>
    <script>
        // 异步操作 文件操作  网络操作(ajax request) 数据库操作
        
        //需求 1s 后控制输出111 2s后输出222  3s后输出333
        //使用定时器做  回调地狱
        setTimeout(()=>{
            console.log('111');
            setTimeout(()=>{
                console.log('222');
                setTimeout(()=>{
                    console.log('333')
                },3000)
            },2000)
        },1000)

        // 使用生成器做
        function one(){
            setTimeout(()=>{
                console.log('111')
                iterator.next();
            },1000)
        }
        function two(){
            setTimeout(()=>{
                console.log('222')
                iterator.next();
            },2000)
        }
        function three(){
            setTimeout(()=>{
                console.log('333')
                iterator.next();
            },3000)
        }

        function * gen(){
            yield one();
            yield two();
            yield three();
        }
        //调用生成器函数
        let iterator = gen();
        iterator.next();
    </script>
</body>
</html>